Need to make grass available for chickens

For the past month my free ranging chickens have been penned up in the run due to a fox coming around and picking them off. The run is nothing but dirt now because they ate all the grass. They seem bored and are pecking at each other. I do offer scratch and throw in grass sometimes, but seems only to keep them busy for a few minutes. I would like them to have access to bugs and grass while being safe. I'm having a hard time trying to figure out what to do. The coop is 8x8x8, on 4 legs that raise the coop of the ground about 2ft. The run is attached and allows access under the coop also.
Would it be possible to somehow be able to move it frequently, to allow access to fresh grass? We have a tractor we could pull it. Maybe we could add some wheels or something? I just don't know if it's to big for that. Any ideas?

I can remove the run if I have to. I also was thinking of getting rid of the run altogether, and buying electric poultry netting. But I would still like to be able to pull the coop to a fresh area once in awhile. Maybe I'll save the run that's attached for the winter and cover with plastic, and use the netting when there's is no snow.
But what would be the best way to move a coop of this size?
As for the fox, I would love to take it out but I don't want to spend countless hours waiting for a fox that may or may not show up. And I have read eventually another will take its place.

I know the chicken wire isn't predator poof, but the coop is right up by the house. It would have to work a decent amount to get in, by then I would know something was up. I'm home all the time. If I'm gone I put them in coop.
As far as expanding the run, I have heard the fly over mostly any height fence. Would I have to cover the top?

I can remove the run if I have to. I also was thinking of getting rid of the run altogether, and buying electric poultry netting. But I would still like to be able to pull the coop to a fresh area once in awhile. Maybe I'll save the run that's attached for the winter and cover with plastic, and use the netting when there's is no snow.
But what would be the best way to move a coop of this size?
As for the fox, I would love to take it out but I don't want to spend countless hours waiting for a fox that may or may not show up. And I have read eventually another will take its place.

Click to expand...

An 8X8 building is pretty large and heavy. You don't want to accidentally damage the structure. Maybe try to find an old trailer axle to bolt to the underside?

I know the chicken wire isn't predator poof, but the coop is right up by the house. It would have to work a decent amount to get in, by then I would know something was up. I'm home all the time. If I'm gone I put them in coop.
As far as expanding the run, I have heard the fly over mostly any height fence. Would I have to cover the top?

Click to expand...

A fox can get through chicken wire in a fairly short amount of time. A bit of chewing and pulling, and it's in. Most chickens can fly over any fence, but they really have to want too. As long as there is enough in the run to keep them occupied, it's not much of an issue.

Since the run can be moved, why not just do that? Move it to another side of the coop where there is still grass. When that section gets thin move it again and so on, 'rotating' your run so nature can keep up with your flock.